The unit used to measure electric current is the ampere (A). Now, assume that the current delivered at a wall socket reaches the value 3.8 A ten times in a time interval of 0.17 s. What is the period T with which the current at the wall socket changes?

T = 0.017s

Explanation:

period is the time it takes a particle to make one oscillation

An electric current is periodic in nature

The current reaches 3.8A  ten times.  

So there must have been 10 cycles (10 periods) in 0.17s.   let 'T'  be the period:

t is the total time interval

n is the number of oscillations

10T = 0.17

T = 0.17/10 = 0.017s

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s